The present invention relates to oral vaccines comprising cationic liposomes and, complexed or entrapped within the liposomes, a gene vaccine, that is a nucleic acid coding for an antigen against which vaccination is desired.
In WO-A-9810748 gene vaccines are described comprising nucleic acid encoding antigen against which vaccination is required, in which the nucleic acid is entrapped within the liposomes. The liposomes are formed from liposome forming components including cationic lipid. The compositions are said to be suitable for administration by, inter alia, oral routes but in the examples, the compositions are administered intramuscularly, subcutaneously, intravenously or intraperitoneally.
For a vaccine to generate an immune response following oral administration, the composition must interact with the lymphoid system in the gut. The vaccine must consequently be stable in the GI tract, and must be stable enough to interact with the relevant cells of the system before being destroyed by bile salts. Clearly it is desirable for vaccines to be administratable orally rather than having to be injected. The present invention relates to compositions which are suitable for oral administration and to oral vaccines and methods for vaccinating human or non human animals by oral administration of the vaccines.